Heart disease, including cardiac arrest, is the most frequently occurring cause of death in the USA (Heron, NVSR, 2015). From the cases that experienced a witnessed out of hospital cardiac arrest (OHCA), overall survival was 11.7% (Ewy et al., 2015). These outcomes, however, are dependent on multiple patient related and non-patient related factors (Shah et al., 2014; Mosier et al., 2010; Hasan et al., 2014; Mauri et al., 2015; Warren et al., 2015; Iqbal et al., 2015).
Predicting patients' functional outcome in early stages after OHCA is difficult. Often the Cerebral Performance Category (CPC) at discharge is used as a quick screening instrument/tool. An overall good neurological outcome, defined as a CPC score of 1 or 2 at discharge, is reported in 6.5% of patients after witnessed OHCA (Ewy et al., 2015). However, the CPC score alone is not sufficient to assess patients' functioning (Wallin et al., 2014). In survivors of OHCA between 30% and 50% experience cognitive deficits up to several years post-discharge (Green et al., 2015). Also cognitive impairment, mainly memory problems, is present in 29% of OHCA survivors with initial good neurological outcome at hospital discharge (Buanes et al., 2015). Especially spatial memory is affected due to ischemia-induced neuronal damage in the hippocampus.
To improve survival and to decrease the degree of neurological impairment, the implementation of therapeutic hypothermia after OHCA has been investigated. No difference in cognitive function was demonstrated between patients who received hypothermia (32° C.-34° C.) and controlled normothermia (36° C.) (Lilja et al., 2015). For that reason new strategies are being explored to reduce the consequences on cognition after cerebral hypoxia-ischemia, such as after OHCA and other diseases in which ischemia and reperfusion injury takes place.